Tyrion exchanges a few words with his father, including revealing that he loved and killed Shae.

During the exchange, Tywin tries to deny Tyrion as his son but he corrects him. "I am your son. I have always been your son," Tyrion says. Then, he puts a second arrow into his chest using King Joffrey's crossbow. (Tyrion later flees Kings Landing.)

Earlier in the episode, Cersei reveals that her offspring were born through incest. She gives Tywin this piece of information as blackmail, saying that she'll come clean about the truth if he makes her marry. Tywin's children have clearly rebelled against him kicking off a major power shift to look forward to in the next season.